1. Field of the Invention
The invention relates in general to a method and an apparatus for fastening adjustable optical lenses. The method and the apparatus can be adapted for an optical scanner.
2. Description of the Related Art
With improvement of software and hardware, a scanner has become a requisite for many computer users. A scanner can scan word or image data of a document, a magazine, a book or a picture, and for input to a computer to process. Among various scanners, the most popular one is flatbed scanner where there is a scanning chassis mounted under a transparent flatbed and capable of reciprocating to scan a document placed on the transparent flatbed. The scanning chassis can not move by itself and it must be driven by a transmission, such as a servomotor, gear wheels, a belt and so on. When a flatbed scanner is used to scan a document, the document is placed on the transparent flatbed, and then a document cover covers the document to press the document so that the document can lie evenly on the transparent flatbed. Next, the scanner can scan the document.
As shown in FIG. 1, there is a scanning chassis of a conventional optical scanner. A light source 100, a reflector group 400, an optical-lens assembly 500, and an optical sensor, such as charged couple device (CCD) 600, are mounted in a case 700 of the scanning chassis. During scanning, after the light source 100 illuminates a document 200, an image of the document 200 can be obtained. The reflector group 400 is composed of many reflectors 401, 402, 403 that reflect the image of the document 200 to transmit it to the optical-lens assembly 500. The optical-lens assembly 500 can receive the image, transmitted by the reflector group 400, of the document 200 and can form the image onto the charged couple device 600.
As shown in FIG. 2, the conventional optical-lens assembly 500 includes an optical-lens group 510, composed of many optical lenses 511, 512, 513, and a round optical-lens sleeve 520 where the optical-lens group 510 is mounted. Before the fabrication of the optical-lens assembly 500 is completed, the adjustment of the relative positions between optical lenses 511, 512, 513 is completed. Afterwards, the optical-lens assembly 500 is directly mounted on a round sleeve 710 of the case 700 by a method for coordinating a shaft and a hole. After the adjustment of the distance between the optical-lens assembly 500 and the charged couple device 600 is completed, a process of coating an adhesive or that of screwing screws is used to fix the optical-lens assembly 500 on the round sleeve 710.
As above mentioned, the method for fabricating the conventional optical-lens assembly 500 includes the adjustment of the optical lenses 511, 512, 513 when mounted on the round optical-lens sleeve 520 and further includes the adjustment of the distance between the optical-lens assembly 500 and the charged couple device 600 when the optical-lens assembly 500 is mounted on the round sleeve 710. Therefore, the method for fabricating the conventional optical-lens assembly 500 needs many adjusting processes, so the time and cost for fabricating it dramatically increases.